Homemade submarine by 60-year-old Chinese farmer successfully dives in river

Villagers lining the banks of the Fengle River in eastern China looked on in awe this week as a sleek black hull slid beneath the surface with a low mechanical rumble.

This wasn’t a military test. It was the homemade invention of Zhang Shengwu, a 60-year-old farmer from Hanshan County in Anhui province, about 250 miles west of Shanghai, who has spent nearly a decade turning a dream into a five-ton, two-seater submarine he calls Big Black Fish.

(Zhang’s boatbuilding has become a viral sensation in China. Photo: Handout)

According to China Daily, Zhang grew up near the Yangtze River basin in Anhui, a rural province in eastern China known for its patchwork of rivers and farmland, earning a living over the years as a carpenter, welder, and even working in the shipping industry. “I’d watched boats all my life,” he told Dawan News, “but I always felt something was missing.”

That sense of possibility crystallized in 2014 when a television program showed a submarine disappearing beneath the waves. “I’d seen wooden and iron boats,” he recalled, “but never one that could go underwater.”

Within days, he borrowed and saved 5,000 yuan (about US$700), bought scrap steel plate, an engine, and a battery, and began welding at night while his wife was caring for her mother, SCMP reports.

(The homemade submarine made by Chinese farmer Zhang Shengwu is lowered into a river in Hanshan county on July 2. Photo: AFP)

Over several months, his first submarine, 19 feet (6 meters) long, 3.9 feet (1.2 meters) high, and weighing two tons, was ready for its first dive. The one‑man sub could submerge just a meter and leaked badly, but it was enough to earn a national utility‑model patent in 2016, according to QQ.com. “I was sweating the whole time,” Zhang admitted, “afraid of leaks, but excited to go deeper.”

Unsatisfied, the self‑taught inventor poured more than 40,000 yuan (US$5,570) into a second‑generation vessel.

Launched this month, Big Black Fish is 22 feet (7 meters) long and 5.9 feet (1.8 meters) high, seats two people and can dive to 8 meters (26 feet), according to Chinese state media.

(Zhang’s Big Black Fish submerges in a river in Hanshan county. Photo: AFP)

Zhang added about two tons of concrete at the bottom to keep the submarine steady underwater and installed water tanks at both ends.

These tanks fill with water to help the vessel dive and drain to rise back up.

Every weld has been reinforced and sealed with silicone, and the cockpit sports a glowing blue instrument panel and an external joystick wrapped in anti‑slip rubber for steering.

The craft cruises at roughly four knots; a five‑metre pole topped with a waterproof camera lets Zhang inspect the riverbed before each dive. He even located a fisherman’s lost net during testing, earning a 3,000 yuan ($417) reward.

Footage of Big Black Fish’s maiden dive, posted on Douyin (China’s version of TikTok) on Wednesday, has ricocheted across Chinese social media.

Although experts have yet to weigh in on the submarine’s safety or seaworthiness, the images, a dark steel hull slipping beneath muddy water, then resurfacing with a hiss, have captured the public imagination.

Ref: Homemade submarine by 60-year-old Chinese farmer successfully dives in river (interestingengineering) Photo Credit-Handout, AFP